#1 and #2 are both possible but #1 is the more usual word order.
#3 is correct. #4 is normally incorrect (it may be just about possible in a certain special sense of “mother”, such as a “pretend” sense, but that is obviously not intended here).
“we all were” and “we were all” both mean “all of us were”. In “we were all delighted”, “all” is understood to modify “we” not “delighted”. In informal language it is possible for “all” to modify a following adjective, as in “I came over all funny”, but that is not how it would be read here.